Messages in this thread | | | Date | Wed, 6 Sep 2023 13:59:55 +0100 | Subject | Re: [PATCH v2 1/1] iommu/arm-smmu-v3: Fix error case of range command | From | Robin Murphy <> |
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On 2023-09-06 06:05, Easwar Hariharan wrote: > On 8/25/23 01:12, zhurui wrote: >> On 2023/8/19 0:21, Will Deacon wrote: >>> On Fri, Aug 18, 2023 at 05:19:31PM +0100, Robin Murphy wrote: >>>> On 2023-08-09 14:48, Robin Murphy wrote: >>>> [...] >>>>> Does the patch below work for you? >>>> >>>> Any comments on this? Just noticed this commit on a local dev branch >>>> and >>>> realised I'd totally forgotten about it already. I'm pretty >>>> confident it >>>> ought to be right, but then it *was* also me who missed the original >>>> bug to >>>> begin with... ;) >>> >>> I'm happy to take it if zhurui can confirm that it fixes their issue... >>> >>> Will (had also forgotten about this) >>> >>>>> ----->8----- >>>>> Subject: [PATCH] iommu/arm-smmu-v3: Avoid constructing invalid range >>>>> commands >>>>> >>>>> Although io-pgtable's non-leaf invalidations are always for full >>>>> tables, >>>>> I missed that SVA also uses non-leaf invalidations, while being at the >>>>> mercy of whatever range the MMU notifier throws at it. This means it >>>>> definitely wants the previous TTL fix as well, since it also doesn't >>>>> know exactly which leaf level(s) may need invalidating, but it can >>>>> also >>>>> give us less-aligned ranges wherein certain corners may lead to >>>>> building >>>>> an invalid command where TTL, Num and Scale are all 0. It should be >>>>> fine >>>>> to handle this by over-invalidating an extra page, since falling >>>>> back to >>>>> a non-range command opens up a whole can of errata-flavoured worms. >>>>> >>>>> Fixes: 6833b8f2e199 ("iommu/arm-smmu-v3: Set TTL invalidation hint >>>>> better") >>>>> Reported-by: Rui Zhu <zhurui3@huawei.com> >>>>> Signed-off-by: Robin Murphy <robin.murphy@arm.com> >>>>> --- >>>>> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 15 ++++++++++----- >>>>> 1 file changed, 10 insertions(+), 5 deletions(-) >>>>> >>>>> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c >>>>> b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c >>>>> index 9b0dc3505601..6ccbae9b93a1 100644 >>>>> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c >>>>> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c >>>>> @@ -1895,18 +1895,23 @@ static void __arm_smmu_tlb_inv_range(struct >>>>> arm_smmu_cmdq_ent *cmd, >>>>> /* Get the leaf page size */ >>>>> tg = __ffs(smmu_domain->domain.pgsize_bitmap); >>>>> >>>>> + num_pages = size >> tg; >>>>> + >>>>> /* Convert page size of 12,14,16 (log2) to 1,2,3 */ >>>>> cmd->tlbi.tg = (tg - 10) / 2; >>>>> >>>>> /* >>>>> - * Determine what level the granule is at. For non-leaf, >>>>> io-pgtable >>>>> - * assumes .tlb_flush_walk can invalidate multiple levels >>>>> at once, >>>>> - * so ignore the nominal last-level granule and leave TTL=0. >>>>> + * Determine what level the granule is at. For non-leaf, both >>>>> + * io-pgtable and SVA pass a nominal last-level granule >>>>> because >>>>> + * they don't know what level(s) actually apply, so ignore >>>>> that >>>>> + * and leave TTL=0. However for various errata reasons we >>>>> still >>>>> + * want to use a range command, so avoid the SVA corner case >>>>> + * where both scale and num could be 0 as well. >>>>> */ >>>>> if (cmd->tlbi.leaf) >>>>> cmd->tlbi.ttl = 4 - ((ilog2(granule) - 3) / (tg - 3)); >>>>> - >>>>> - num_pages = size >> tg; >>>>> + else if ((num_pages & CMDQ_TLBI_RANGE_NUM_MAX) == 1) >>>>> + num_pages++; >>>>> } >>>>> >>>>> cmds.num = 0; >>>>> >> >> Hi, Will and Robin, >> Sorry for taking so long to reply you. We have some problems with our >> machine these days. It's >> solved just today. I give a test with Robin's patch for our testcase, >> everything is ok. I think >> the problem has been solved. >> >> Thanks, >> ZhuRui. >> > > Hi Robin, > > Could you please send out this patch since ZhuRui has confirmed it fixes > their issue and CC it to stable for v5.15+? Or if Will is willing to > pick it up off this thread, I can do the backport to stable.
I can resend after -rc1 if Will would prefer that. It's tagged as a fix so should hopefully get picked for stable automatically once it hits mainline.
Thanks, Robin.
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